Lattice boiler evaporator

ABSTRACT

An evaporator suitable for a thermal dissipation module. The thermal dissipation module includes a tube or pipe and fluid. The evaporator includes a housing, a first heat dissipation structure and a second heat dissipation structure disposed in a sealed chamber of the housing. The chamber is configured to communicate with the pipe, and the fluid is configured to flow in the pipe and the chamber. The first heat dissipation structure and a second heat dissipation structure provide a plurality of fluid flow passages through which the fluid flows and evaporates. A manufacturing method of the evaporator is also disclosed.

TECHNICAL FIELD

Embodiments of the present invention are directed to heat management inan electronic device.

BACKGROUND

Electronic portable devices such as laptops, tablet personal computers(PCs), smart phones and other products are increasingly used in dailylife. Some of the electronic components employed by these electronicdevices generate thermal energy (heat) during operation, which, in orderfor the device to operate properly, must be dissipated. In this regard,a cooling module or a heat sink, in the form of, e.g., a cooling fan, aheat pipe, or a two-phase siphon cooling system (or two-phasethermosiphon cooling system) may be incorporated inside the electronicdevice to assist in dissipating excess heat.

The heat dissipation efficiency of a heat conductive sheet or heat pipeis limited, however, so a cooling fan is often employed in combinationtherewith. However, the operation of a cooling fan relies on powerprovided by a battery of the electronic device, leading to increasedconsumption of that limited battery power. While some electronic deviceshave been designed with a two-phase siphon cooling system, such a systemtypically requires a fluid to circulate in a pipeline as a result of adifference of potential energy (height) and the gravitational forceamong the fluid molecules. When the relative state between theelectronic device and the gravitational direction changes, theefficiency of such a cooling system decreases.

SUMMARY

The present invention provides an evaporator which can improve thecirculation efficiency of the fluid in a heat dissipation module.

The present invention further provides a method of manufacturing anevaporator that can improve product yield and reduce manufacturingcosts.

The evaporator of the present invention is suitable for use in a heatdissipation module in which the heat dissipation module comprises a tubeand a fluid. The evaporator includes a housing and a first heatdissipation structure. The housing has a chamber for communicating withthe tube, and the fluid is configured to flow in the tube and chamber. Afirst heat dissipation structure is provided in the chamber, wherein thefirst heat dissipation structure has a plurality of first flow passagesand is adapted to cause fluid to flow through the first flow passageswhen the fluid flows in the chamber.

The method of manufacturing the evaporator of the present inventionincludes the following steps. A first heat dissipation structure isformed, wherein the first heat dissipation structure has a plurality offirst flow paths. A housing is formed, wherein the housing has achamber, a first opening and a second opening. The first heatdissipation structure is disposed in the chamber such that the chamberis adapted to allow fluid to flow between the first and second openingsvia the first flow passages.

Based on the above, the evaporator of the present invention is providedwith a first heat dissipation structure in the chamber of the housing,and the first heat dissipation structure has a plurality of first flowpassages for passage of the fluid. This arrangement helps to increasethe contact area between the fluid and the housing to increase the rateof vaporization of the fluid after the housing has received heat fromthe electronic component or heat pipe. The fluid in the circuit formedby the tube and chamber undertakes a change of state in the chamber(i.e., the fluid evaporates), resulting in a cooling effect.

Notably, the first heat dissipation structure is assembled into thehousing after fabrication. This is in contrast to prior art methods ofevaporator fabrication, wherein such an evaporator structure is etchedor formed by computer numerical control (CNC) tools. Thus, the methodfor producing the evaporator of the invention not only improves productyield but also reduces production cost.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are described herein in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded schematic view of an evaporator according to anembodiment of the present invention;

FIG. 2 is a schematic structural view of the evaporator and a heatdissipation module of FIG. 1 according to an embodiment of the presentinvention;

FIG. 3 is a top view of the evaporator and heat dissipation module ofFIG. 2 according to an embodiment of the present invention; and

FIG. 4 is a cross-sectional view of FIG. 3 taken along line I-Iaccording to an embodiment of the present invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 is an exploded schematic view of an evaporator 100 according toan embodiment of the present invention. FIG. 2 is a schematic structuralview of the evaporator 100 and the heat dissipation module of FIG. 1.FIG. 3 is a schematic top view of the evaporator and heat sink module ofFIG. 2. FIG. 4 is a schematic cross-sectional view of FIG. 3 taken alongline I-I. For clarity and ease of illustration, a lid 140 of FIGS. 2 and3 is depicted transparently. In FIGS. 1 to 4, in the present embodiment,the evaporator 100 may be integrated into or be part of an overall heatdissipation module (including, e.g., a heat pipe 20) and provided in anelectronic apparatus (not shown). The electronic device (not shown) maybe a smart phone, tablet, notebook, docking station or other electronicproduct with an internal electronic component (not shown) such as acentral processing unit or a display chip. The heat sink module may bethermally coupled to an electronic component (not shown) to absorb heatgenerated by the electronic component. In this way, the evaporator 100dissipates the heat generated by the electronic component that has beentransferred via the heat pipe 20.

The evaporator 100 and the heat dissipation module may constitute asiphonic heat dissipation assembly, wherein the heat dissipation moduleincludes a first tube element or pipe 11, a second tube element or pipe12 and a fluid 13 (see, e.g., FIGS. 2 and 3, the flow of which isdenoted by arrows. First tube element or pipe 11 and second tube elementor pipe 12 are respectively communicated with the evaporator 100, andthe fluid 13 is configured to flow in the first pipe 11, the second pipe12, and the evaporator 100. The evaporator 100 may include a housing 110having a chamber 111, a first opening 112, and a second opening 113 withrespect to the first opening 112, a first heat dissipation structure120, a second heat dissipation structure 130, and a cover or lid 140.The first opening 112 and the second opening 113 are communicated withthe chamber 111, respectively. The first pipe 11 is disposed in thefirst opening 112 and communicates with the chamber 111. The second pipe12 is disposed in the second opening 113. As such, the fluid 13 may flowinto the chamber 111 via the first pipe 11 and out of the chamber 111via the second pipe 12. The end of the second pipe 12 may be directlyconnected to the first pipe 11, i.e., end portions of the same tubularmember function as the first pipe 11 and the second pipe 12,respectively, or the end of the first pipe 11 may be indirectlyconnected to the end of the second pipe via a condenser (not shown). Thefirst pipe 11 is connected to allow the fluid 13 to flow from the secondpipe 12 out of the chamber 111 and continue to flow to the first pipe 11and back into the chamber 111. In other words, the first pipe 11, thesecond pipe 12, and the chamber 111 may constitute a circuit forcirculating a flow of the fluid 13.

In the present embodiment, the chamber 111 may be divided into a firstevaporation zone 111 a and a second evaporation zone 111 b. The firstevaporation zone 111 a and the second evaporation zone 111 b may bethermally coupled to the housing 110 through the heat pipe 20. In theembodiment shown, the heat pipe 20 is located directly under the firstevaporation zone 111 a. The heat of the heat pipe 20 can thus beconducted into the chamber 111 via the housing 110. After the fluid 13flows into the chamber 111 through the first pipe 11, the fluid 13 flowsthrough the first evaporation zone 111 a and the second evaporation zone111 b, respectively, and absorbs heat. The phase of the fluid 13, inliquid form, may be converted to gaseous fluid 13 (evaporation) and heatis thus removed as gaseous fluid 13 flows out of chamber 111 via thesecond pipe 12. Thereafter, the fluid 13, in a gaseous state, can bere-condensed as the second pipe 12 and the first pipe 11 pass throughlower temperature portions of the electronic device (not shown), suchthat the heat is dissipated to the outside world. Fluid 13, which hasbeen converted from the gaseous state back to the liquid state, may thenbe returned to the chamber 111 via the first pipe 11.

The first heat dissipation structure 120 and the second heat dissipationstructure 130 are juxtaposed in the chamber 111, viewed from the firstopening 112 toward the second opening 113, and the second heatdissipation structure 130 is arranged rearward of the first heatdissipation structure 120, as shown in FIG. 2. The first heatdissipation structure 120 and the second heat dissipation structure 130may be fixed to the housing 110 by welding, for example, by using asolder paste or other solder between the first and second heatdissipation structures 120, 130 and the housing 110. The first andsecond heat dissipation structures 120 and 130 are respectively heatedby the housing 110 and the first heat dissipation structure 120 and thesecond heat dissipation structure 130 are welded to the chamber 110.

In other embodiments, however, a heat-conducting medium such as athermally conductive paste may be used between the first and second heatdissipating structures 120, 130 and the housing 110, or the first andsecond heat dissipating structures 120, 130 may be simply brought intocontact with the housing 110 without welding. The cover or lid 140 isdisposed on the housing 110 and covers the chamber 111 and the first andsecond heat dissipation structures 120, 130 disposed in the chamber 111so that the chamber 111 is sealed to the outside. That is, once thecover 140 covers the chamber 111, the chamber 111 constitutes a closedspace with the only ingress and egress via the first pipe 11 and thesecond pipe 12, respectively.

Preferably, the engagement of the cover 140 with the housing 110 may beprovided with a leak-proof structure to prevent leakage of the fluid 13from the chamber 111. In this regard, the cover 140 may be welded to thehousing 110 to seal the chamber 111. More specifically, the housing 110includes a bearing surface 114 on which cover 140 may be disposed. Thebearing surface 114 substantially conforms to, i.e., is at the sameheight as, a first upper surface 123 of the first heat dissipationstructure 120 and a second upper surface 133 of the second heatdissipation structure 130 such that the cover 140 abuts against thebearing surface 114, the first upper surface 123 and the second uppersurface 133. Thus, the first heat dissipation structure 120 and thesecond heat dissipation structure 130 also support the cover 140.

As shown in the figures, the first heat dissipation structure 120 islocated between the first opening 112 and the second heat dissipationstructure 130, and the second heat dissipation structure 130 is locatedbetween the first heat dissipation structure 120 and the second opening113. The first heat dissipation structure 120 spans a first evaporationzone 111 a and a second evaporation zone 111 b and has a plurality offirst flow passages 121 and 122, and similarly, the second heatdissipation structure 130 spans the first evaporation zone 111 a and thesecond evaporation zone 111 b, and has a plurality of second flow paths131 and 132. Accordingly, the fluid 13 flowing from the first opening112 into the chamber 111 first passes through the first flow passages121 and 122, passes through the second flow passages 131 and 132, andfinally flows out of the chamber 111 via the second opening 113.

The first heat dissipation structure 120 may be constituted by aplurality of first structural members 120 a and 120 b interconnectedwith one another. The first flow passages 121 may be defined by theinterconnected first structural members 120 a, and the first flowpassages 122 may be defined by the interconnected first structuralmembers 120 b. In the embodiment shown, a depth D1 of the firstevaporation zone 111 a is less than a depth D2 of the second evaporationzone 111 b. The first structural members 120 a are disposed in the firstevaporation zone 111 a and the height of the first structural members120 a is substantially equal to depth D1. The first structural members120 b are disposed within the second evaporation zone 111 b and theheight of the first structural members 120 b is substantially equal tothe depth D2. The number of the first structural members 120 b is, forexample, larger than the number of the first structural members 120 a,and the first structural members 120 a and 120 b may have two differentsizes, respectively. As such, the first flow passages 121 located in thefirst evaporation zone 111 a have a different cross-sectional areacompared to the first flow passages 122 located in the secondevaporation zone 111 b, and the number of the first flow passages 121 issmaller than the number of the first flow passages 122.

The second heat dissipation structure 130 may be constituted by aplurality of second structural members 130 a and 130 b, and the secondflow passages 131 may be defined by the interconnected second structuralmembers 130 a. The second flow passages 132 are defined by the secondstructural members 130 b. In the embodiment shown, the second structuralmembers 130 a are disposed in the first evaporation zone 111 a and theheight of the second structural members 130 a is substantially equal tothe depth D1. The second structural members 130 b are disposed in thesecond evaporation zone 111 b and the height of the second structuralmembers 130 b is substantially equal to the depth D2. The number of thesecond structural members 130 b is, for example, larger than the numberof the second structural members 130 a such that the second structuralmembers 130 a and 130 b have two different sizes, respectively. As such,the second flow passage 131 in the first evaporation zone 111 a have adifferent cross-sectional area compared to the second flow passages 132in the second evaporation zone 111 b, and the number of the second flowpassages 131 is smaller than the number of the second flow passages 132.

In the present embodiment, the first structural members 120 a and 120 band the second structural members 130 a and 130 b are long slats eachhaving a C-shaped cross section, and can be engaged with each other in arow so that the first flow passages 121, 122 and the second flowpassages 131, 132 are formed between the members. However, in otherembodiments, the first structural members 120 a, 120 b and the secondstructural members 130 a, 130 b may have an L-shaped, inverted T-shapedor Z-shaped cross-sectional shape.

With reference still to FIGS. 1-4, the number of second structuralmembers 130 a is equal to the number of first structural members 120 a,and the number of second structural members 130 b is less than thenumber of first structural members 120 b. The cross-sectional area ofthe first flow passages 122 is, for example, smaller than thecross-sectional area of the second flow passages 132, and thecross-sectional area of the first flow passages 121 is equal to thecross-sectional area of the second flow passages 132. The number of thefirst flow passages 122 is greater than the number of second flowpassages 132. As will be appreciated by those skilled in the art, thefirst and second heat dissipation structures 120 and 130 are designedprimarily to increase the contact area between the fluid 13 and thehousing 110.

In the instant embodiment, since the number of the first flow passages122 is, for example, larger than the number of the second flow passages132, the contact area of the first heat dissipation structure 120 withthe fluid 13 may be larger than that of the second heat dissipationstructure 130. As a result, the rate of vaporization of the fluid 13flowing through the first heat dissipation structure 120 may be greaterthan the rate of vaporization of the fluid 13 flowing through the secondheat dissipation structure 130. As such, dynamic pressure (e.g., apressure difference) of the fluid will drive vaporized fluid 13 towardthe second opening 113. As a result, the circulation effect of the fluid13 in the circuit formed by the first pipe 11, the second pipe 12, andthe chamber 111 can be remarkably increased.

The average cross-sectional area of the first flow passages 122 issmaller than the average cross-sectional area of the second flowpassages 132 in the second evaporation zone 111 b and, therefore, in thefirst flow passages 122 bubbles generated by the vaporized fluid 13 arerelatively dense, and the volume of bubbles generated by the fluid 13vaporized in the second flow path 132 is larger than in the first flowpassages 122. As a result, there is a pressure difference between wherethe first flow passages 122 and the second flow passages 132 arelocated, through which the gaseous fluid 13 is driven, therebyincreasing the flow rate of the fluid 13 (including the liquid state andthe gaseous state) in the circuit formed by the first pipe 11, thesecond pipe 12, and the chamber 111.

Further, since the bubbles generated by the vaporized fluid 13 in thefirst flow passages 122 are relatively dense and the cross-sectionalarea of the second flow passages 132 is, for example, larger than thecross-sectional area of the first flow passages 122, the bubblesgenerated by the vaporized fluid 13 within the first flow passages 122pass smoothly through the second flow passage 132 without beingobstructed therein.

In the present embodiment, the first heat dissipation structure 120 hasmore first structural members 120 a and 120 b than the second structuralmembers 130 a and 130 b provided in the second heat dissipationstructure 130, so that the first flow passages 121, 122 have a smallertotal cross sectional area than the total cross-sectional area of thesecond flow paths 131 and 132. As a result, the first heat dissipationstructure 120 has a larger flow resistance than the second heatdissipation structure 130. When the fluid 13 in chamber 111 vaporizes,the fluid 13 tends to flows in the direction of the lower flowresistance, and this contributes to the flow of the fluid 13 in thedirection of the second structural members 130 a, 130 b and the secondopening 113.

In the present embodiment, the housing 110 further has a firstpositioning portion 115, a second positioning portion 116, and a thirdpositioning portion 117, which each protrude into the chamber 111. Thefirst positioning portion 115, the second positioning portion 116, andthe third positioning portion 117 have, for example, a lateral rib shapeand are configured to lay across the first evaporation zone 111 a andthe second evaporation zone 111 b with respect to the flow direction ofthe fluid 13.

With particular reference now to FIGS. 2 and 3, the first positioningportion 115 is located between the second positioning portion 116 andthe first opening 112, and the second positioning portion 116 is locatedbetween the first positioning portion 115 and the third positioningportion 117. The third positioning portion 117 is located between thesecond positioning portion 116 and the second opening 113. The firstheat dissipation structure 120 is disposed between the first positioningportion 115 and the second positioning portion 116. By employing thefirst positioning portion 115 and the second positioning portion 116, itis possible to facilitate assemblage of the first heat dissipationstructure 120 within the housing 110. The second heat dissipationstructure 130 is disposed between the second positioning portion 116 andthe third positioning portion 117. By employing the second positioningportion 116 and the third positioning portion 117, it is possible tofacilitate assemblage of the second heat dissipation structure 130within the housing 110.

In an alternative embodiment, the second positioning part 116, locatedbetween the first heat dissipation structure 120 and the second heatdissipation structure 130, can separate the two structures, therebyincreasing the flow of the fluid 13 from the first flow paths 121 or 122to the second flow paths 131 or 132 so that the bubbles generated by thefluid 13 vaporized in the first flow paths 121 and 122 may flow into thesecond flow paths 131 or 132 according to the shortest path.

In the present embodiment, as shown in FIGS. 1 and 2, a method ofmanufacturing the evaporator 100 includes the steps of first forming thehousing 110, the cover 140, and the first and second structural members120 and 130, respectively. The housing 110 is formed, for example, byforging, casting or cutting. The first structural members 120 a, 120 band the second structural members 130 a, 130 b are fabricated, forexample, by forging a plurality of first structural members 120 a, 120 band second structural members 130 a, 130 b. Then, any two adjacent firststructural members 120 a are engaged with each other, and any twoadjacent first structural members 120 b are engaged with each other andone of the first structural members 120 a is engaged with one of thefirst structural members 120 b to constitute a first heat dissipationstructure 120 having a plurality of first flow passages 121 and 122.Similarly, any two adjacent second structural members 130 a are engagedwith each other, and any two adjacent second structural members 130 bare engaged with each other and one of the second structural members 130a is engaged with one of the second structural members 130 b toconstitute a second heat dissipation structure 130 having a plurality ofsecond flow passages 131 and 132.

Next, the first heat dissipation structure 120 and the second heatdissipation structure 130 are assembled in the chamber 111, and thefirst heat dissipation structure 120 and the second heat dissipationstructure 130 are fixed to the housing 110 by soldering. As shown, boththe first and second heat dissipation structures 120 and 130 aredisposed across the first evaporation zone 111 a and the secondevaporation zone 111 b. Thereafter, the cover or lid 140 is provided onthe housing 110, and the cover 140 covers the chamber 111 and the firstand second heat dissipation structures 120 and 130 disposed in thechamber 111. Soldering with solder paste, between the first heatdissipation structure 120 and the housing 110, between the second heatdissipation structure 130 and the housing 110, and between the cover 140and the housing 110 may be completed by a single heat welding operationafter the assembly is completed. The manufacturing method of theevaporator 100 of the present embodiment can not only improve thequality of the product, but can also improve the producibility of theproduct by, for example, avoiding etching or machining with a computernumerical control tool, and therefore also reduce production costs.

In another embodiment, the first structural members 120 a, 120 b of thefirst dissipation structure 120 and the second structural members 130 a,130 b of the second heat dissipation structure 130 may be directlyassembled in the chamber 111 after the forging and molding processes,without the step of first engaging individual elements thereof with eachother.

In sum, and as described above, the evaporator of the present inventionis provided with a first heat dissipation structure and a second heatdissipation structure in a chamber of the housing, and the first heatdissipation structure and the second heat dissipation structure have aplurality of first flow passages and a plurality of second flow passagesfor passing a fluid. With this arrangement, the contact area between thefluid and the housing is increased to increase the vaporization rate ofthe fluid. More specifically, since the number of the first flowpassages located in the second evaporation zone is larger than thenumber of the second flow passages located in the second evaporationzone, and the cross-sectional area of the first flow passages located inthe second evaporation zone is smaller than that of the second flowpassages there will be a pressure difference between the first flowpassages located in the second evaporation zone and the second flowpassages located in the second evaporation zone after the vaporizationof the fluid, thereby smoothly driving the fluid in a gaseous state outof the chamber via the second opening in the chamber.

Moreover, the first heat dissipation structure and the second heatdissipation structure of the present invention can be produced byforging and engaging steps, etc., and then assembled into the housing,precluding the need for more expensive and time consuming cuttingoperations using etching or computer numerical control tools. The methodfor manufacturing the evaporator of the present invention can not onlyimprove product yield and production efficiency, but can also reduceproduction costs.

The above description is intended by way of example only.

What is claimed is:
 1. A method of manufacturing an evaporator,comprising: forming a first heat dissipation structure having aplurality of first flow passages; forming a second heat dissipationstructure having a plurality of second flow passages; forming a housinghaving a chamber, a first opening and a second opening; disposing thefirst heat dissipation structure and the second heat dissipationstructure in the chamber such that the chamber is configured to enable aflow of fluid between the first opening and the second opening via thefirst flow passages and the second flow passages, sequentially, whereinthe chamber comprises a first evaporation zone and a second evaporationzone disposed between the first opening and the second opening, thefirst evaporation zone being separated from the second evaporation zone,and the first heat dissipation structure spans the first evaporationzone and the second evaporation zone on respective sides of the chamber,and arranging the housing to be in contact with, and over, a heat pipesuch that the first evaporation zone overhangs the heat pipe, and atleast the first flow passages in the second evaporation zone have adepth such that lower surfaces of at least the first flow passages inthe second evaporation zone extend below a plane defined by respectivecontacting surfaces of the heat pipe and the housing.
 2. The method ofmanufacturing an evaporator according to claim 1, wherein the firstevaporation zone and the second evaporation zone are arranged onrespective sides of the chamber, the first heat dissipation structurespanning the first evaporation zone and the second evaporation zone. 3.The method of manufacturing an evaporator according to claim 1, whereina cross-sectional area of the first flow passages is smaller than across-sectional area of the second flow passages.
 4. The method ofmanufacturing an evaporator according to claim 1, wherein the step offorming the first heat dissipation structure includes: forging a metalto form a plurality of C-shaped structural members; arranging thestructural members side by side with each other so that a given one ofthe first flow passages is formed between any two adjacent C-shapedstructural members.
 5. The method of manufacturing an evaporatoraccording to claim 1, further comprising: providing a cover on thehousing after the first heat dissipation structure is disposed in thechamber.
 6. The method of manufacturing an evaporator according to claim1, wherein the step of disposing the first heat dissipation structure inthe chamber includes welding and bonding the first heat dissipationstructure to the housing.